From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: default timer_mode in xen and in libxl
Date: Thu, 25 Apr 2013 18:25:23 +0100
Message-ID: <CD9F2593.50A40%keir.xen@gmail.com>
References: <alpine.DEB.2.02.1304251810470.4180@kaball.uk.xensource.com>
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>, xen-devel@lists.xensource.com
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>, Ian Campbell <Ian.Campbell@citrix.com>
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On 25/04/2013 18:13, "Stefano Stabellini" <stefano.stabellini@eu.citrix.com>
wrote:

> Hi all,
> I have just noticed that the timer mode default in libxl is not the
> default in Xen.
> The Xen default is HVMPTM_delay_for_missed_ticks, while libxl by
> default sets it to LIBXL_TIMER_MODE_NO_DELAY_FOR_MISSED_TICKS that
> obviously is HVMPTM_no_delay_for_missed_ticks.
> 
> Is there a reason for this?
> If so, should we change the defalt in Xen too?

Default in Xen is the original mode before multiple modes were supported. We
kept that as default for old/other toolstacks, to avoid surprising change in
behaviour (e.g., when they restore old saved guests).

Default in libxl is the sane one for newly-created guests. Hardly any guests
care about or even want time to be delayed until timer interrupts are fired
off.

 -- Keir

> commit 2d058a444a1fa71ec47a673d08c2e74790ae67fb
> Author: Ian Campbell <ian.campbell@citrix.com>
> Date:   Thu Mar 1 12:26:13 2012 +0000
> 
>     libxl: use an explicit LIBXL_TIMER_MODE_DEFAULT value
>     
>     Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
>     Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
> 
> 
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